New contraceptive vaccines, implants may prove promising
Contraceptive Technology Update 13(1): 18-19
1992
ISSN/ISBN: 0274-726X PMID: 12343461 Document Number: 294280
There are several possible new contraceptives on the horizon. For example, there are at least four second generation Silastic implant contraceptives similar to Norplant in development. These new systems have fewer numbers of implants than Norplant, which will make removal easier. Norplant 2 consists of only two rod implants instead of the six in the original Norplant system, while single-implant systems are also being developed. A biodegradable implant is also being researched; such a device would not have to be removed once its expected period of service transpired. A vaccine to prevent pregnancy is also being studied, with the most comprehensive research program being conducted currently in India. Vaccine research sponsored by the World Health Organization has also taken place in Australia. A version of a vaccine could be ready in India some time after the year 2000. On yet another front, researchers in China are studying the use of gossypol in a birth control pill for men. Gossypol is a substance found naturally in cottonseed. More than 10,000 Chinese men have taken gossypol, with as many as 99.4% developing lower sperm counts. Findings from some of the gossypol studies, however, indicate a decline in potassium levels in men. Moreover, some studies have shown that after a year of taking gossypol, approximately 80% of men have resumed normal sperm production, but some men remain azoospermic even after several years. The acceptability and usefulness of gossypol as a male contraceptive will clearly be influenced by its reversibility. Synthetic analogues which work either as potent agonists or antagonists of the polypeptide LH-RH, and an injectable pituitary-suppressing dose of androgen, progestin, or a combination of both are also possible male contraceptives. Findings from this latter research have not been promising. The article stresses that much of male contraceptive research is in its early stages.